1. Field of the Invention
The embodiments of the invention generally relate to a method and apparatus for plasma processing a substrate, and more specifically, plasma processing chamber having a ground member integrity indicator and method for using the same.
2. Description of the Related Art
Liquid crystal displays or flat panels are commonly used for active matrix displays such as computer and television monitors. Generally, flat panels comprise two plates having a layer of liquid crystal material sandwiched therebetween. At least one of the plates includes at least one conductive film disposed thereon that is coupled to a power source. Power, supplied to the conductive film from the power supply, changes the orientation of the crystal material, creating a patterned display.
In order to manufacture these displays, a substrate, such as a glass or polymer workpiece, is typically subjected to a plurality of sequential processes to create devices, conductors and insulators on the substrate. Each of these processes is generally performed in a process chamber configured to perform a single step of the production process. In order to efficiently complete the entire sequence of processing steps, a number of process chambers are typically coupled to a central transfer chamber that houses a robot to facilitate transfer of the substrate between the process chambers. A processing platform having this configuration is generally known as a cluster tool, examples of which are the families of AKT plasma enhanced chemical vapor deposing (PECVD) processing platforms available from AKT America, Inc., of Santa Clara, Calif.
As demand for flat panels has increased, so has the demand for larger sized substrates. For example, large area substrates utilized for flat panel fabrication have increased in area from 550 mm by 650 mm to over 2 square meters in just a few years and are envisioned to continue to increase in size in the near future. This growth in the size of the large area substrates has presented new challenges in handling and production. For example, the larger surface area of the substrates requires increased grounding capacity of the substrate supports. On conventional systems, a plurality of flexible conductive straps provides a ground path between the substrate support and chamber body. Since the ground straps are not readily visible from the exterior of the processing chamber, operators are often unaware if one or more straps are broken. If enough straps are broken, processing results may no be within specification, resulting in defects. Although breakage of one strap is not a catastrophic event, strap breakage does affects process uniformity, and as such, the inventors have recognized that would be desirable to be monitor the effectiveness of the substrate support ground in order to maintain robust processing.
Therefore, there is a need for an improved plasma processing chamber having a ground member integrity indicator and method for using the same.